Field of the Invention
Embodiments of the present invention relate to a liquid crystal display device, and more particularly, to a column spacer for maintaining a cell gap of a liquid crystal display device.
Discussion of the Related Art
Owing to advantages such as good portability and low power consumption by low operating voltage, a liquid crystal display (LCD) device is widely used in various fields of notebook computer, monitor, spacecraft, aircraft, and etc.
The LCD device includes a lower substrate with a thin film transistor formed thereon, an upper substrate with a color filter formed thereon, and a liquid crystal layer formed between the lower and upper substrates. Also, a column spacer for maintaining a cell gap between the lower and upper substrates is formed between the lower and upper substrates.
Hereinafter, a related art LCD device will be described with reference to the accompanying drawings.
FIG. 1A is a plane view illustrating the related art LCD device. FIG. 1B is a cross sectional view illustrating the related art LCD device, wherein FIG. 1B is a cross sectional view along A-B line and C-D line of FIG. 1A.
As shown in FIG. 1A, the related art LCD device 1 includes a display area for displaying an image, and a non-display area prepared in the periphery of the display area. A column spacer 30 is provided in each of the display area and the non-display area.
As shown in FIG. 1B, the column spacer 30 is formed between a lower substrate 20 and an upper substrate 10. In more detail, a light-shielding layer 12 is formed in the display area and the non-display area on the upper substrate 10. The column spacer 30 is provided on the light-shielding layer 12. That is, a cross sectional structure of the region with the column spacer 30 in the display area on the upper substrate 10 is identical to a cross sectional structure of the region with the column spacer 30 in the non-display area on the upper substrate 10.
However, in case of the lower substrate 20, a cross sectional structure of the display area is different from a cross sectional structure of the non-display area. That is, in case of the display area, a thin film transistor layer 22 is formed on the lower substrate 20. Meanwhile, in case of the non-display area, the thin film transistor layer 22 is not formed on the lower substrate 20.
In case of the region with the column spacer 30, the cross sectional structure of the display area on the lower substrate 20 is different from the cross sectional structure of the non-display area on the lower substrate 20. In more detail, a distance (D1) between the column spacer 30 and the lower substrate 20 in the non-display area is longer than a distance (D2) between the column spacer 30 and the thin film transistor layer 22 of the lower substrate 20 in the display area.
Accordingly, a cell gap (D1) of the non-display area is larger than a cell gap (D2) of the display area, whereby an entire cell gap of the liquid crystal display device is not uniform.